Certain regions of Earth experience prolonged periods where the sun remains below the horizon. This phenomenon creates unique environments with extended darkness, significantly altering the landscape and its inhabitants.
Geographic Locations
Regions experiencing prolonged periods without sunlight are primarily found within or very close to the Earth’s polar circles. In the Northern Hemisphere, countries like Norway, Sweden, Finland, Russia, Canada, and Greenland contain areas where the sun does not rise for weeks or even months. For example, Tromsø in Norway experiences polar night from November to January, and Utqiaġvik in Alaska experiences polar night from mid-November to mid-January. At the North Pole, the sun sets around the autumnal equinox in September and does not rise again until the vernal equinox in March, resulting in six months of continuous night. In the Southern Hemisphere, Antarctica is the only landmass experiencing polar night, with research stations enduring prolonged darkness during their winter months.
The Science Behind Polar Night
The Earth’s axial tilt is the primary reason certain areas experience periods without direct sunlight. Our planet is tilted on its axis at approximately 23.5 degrees relative to its orbital plane around the sun. This tilt means that as the Earth revolves, different hemispheres are angled either towards or away from the sun at various times of the year. When a hemisphere is tilted away from the sun during its winter, the polar regions within that hemisphere receive little to no direct sunlight.
This astronomical configuration causes the sun to remain below the horizon for extended durations in the high latitudes, a phenomenon known as polar night. The length of this period of darkness increases with proximity to the poles. While the sun’s center may be below the horizon, atmospheric refraction can sometimes cause a small portion of the sun’s disk to be visible, or at least create twilight conditions, preventing complete darkness even during polar night in some areas.
Life in Extended Darkness
Living in regions of extended darkness presents environmental and biological challenges. The absence of direct sunlight contributes to extreme cold temperatures, often accompanied by heavy snow and ice cover, which limits food availability for many organisms. Wildlife in these areas has developed specialized adaptations to cope with these conditions. For example, reindeer have unique eye adaptations allowing them to utilize more ultraviolet light, helping them discern plants in the snow. Many marine animals possess thick blubber or specialized circulatory systems to conserve heat in frigid waters.
Human inhabitants also face adjustments to the prolonged darkness. Seasonal Affective Disorder (SAD), a mood disorder characterized by depressive symptoms, is more prevalent in high-latitude regions due to reduced light exposure. Symptoms can include fatigue, oversleeping, and changes in appetite. Communities often employ strategies like light therapy, active lifestyles, and strong social connections to mitigate these effects. Prolonged darkness and isolation can also lead to irritability, depression, and sleep disturbances, particularly for those in remote research stations.